1. Field of the Invention
The present invention relates to a flash system, and more particularly to a flash system in which a flash device incorporated in or connected to, for example, a camera is used as a master transmission device to control the light emission of a slave flash device located in a remote position.
2. Description of Related Art
Heretofore, there have been known the following wireless flash systems, each of which uses a wireless flash device located in a position distant from a camera.
As a first example, in Japanese Laid-Open Patent Application No. Hei 4-343341, there is disclosed a wireless flash system, in which a flash device mounted on a camera body transmits to a slave flash device a light-emission start signal composed of a plurality of light pulse signals of a predetermined interval, the slave flash device repeats intermittent light emission upon receipt of the light-emission start signal, a light control circuit of the camera integrates reflected light from an object resulting from the light emission of the slave flash device, and when the result of the integration becomes a predetermined amount of light, the flash device mounted on the camera again transmits to the slave flash device a light-emission stop signal during the absence of the light emission of the slave flash device, thereby ending the light emission.
Further, as a second example, in Japanese Laid-Open Patent Application No. Hei 6-180472, there is disclosed a wireless flash system, in which a camera makes communication with a wireless slave flash device by means of an infrared light signal from the camera, a preliminary infrared light emission is performed a predetermined number of times by an infrared light emitting diode incorporated in the wireless slave flash device, and the camera integrates reflected infrared light from an object, computes the amount of light emission for a main light emission and gives to the wireless slave flash device instructions for the amount of light emission for the main light emission and the timing of light emission for the main light emission, so that a photograph is taken with the main light emission of the wireless slave flash device.
However, in the above first example of wireless flash system, there is a drawback that it is impossible to heighten the flash synchronizing speed due to the intermittent light emission, and there is a possibility that a photograph which is to be taken with a small amount of light emission at a near distance becomes overexposed.
Further, since it is impossible to perform wireless flash photography with a long-time light emission, called xe2x80x9cflat emissionxe2x80x9d, used for taking a photograph at a high shutter speed exceeding the flash synchronizing speed, there is a drawback that it is impossible to perform daylight wireless flash photography for which a relatively high shutter speed.
Further, there is a drawback that the guide number of the flash device is lowered by the switching loss occurring in a control circuit due to the intermittent light emission.
In the above second example of wireless flash system, light measurement is performed with the infrared preliminary light emission of the slave flash device and an actual photograph is taken with daylight. Therefore, there is a possibility that an exposure is inaccurately performed due to the difference in reflection factor of infrared ray of an object.
Further, since an infrared light emitting part is required in each of the camera and the slave flash device, there is a drawback that the production cost of the system increases.
In addition, such an infrared light emitting device that uses the infrared light emitting diode can not produce a sufficiently strong light output, and, therefore, the slave flash device can not be located in a distant position, so that a limit is set to the shooting range.
Further, in the above first and second examples of wireless flash systems, there is a description of an automatic light control mode. However, since an exposure is sometimes made uneven depending on the condition of an object if only the automatic light control mode is used in the flash photography, there are provided, other than the automatic light control mode, a manual light emission mode for setting the amount of light emission of the flash device to a fixed setting value, a multiple light emission mode for catching and photographing continuous motions of a moving object, etc., which can not be executed in the above first and second examples.
It is an object of the invention to provide a flash system capable of changing over between a highspeed photography using a shutter speed higher than a flash synchronizing speed and a flash photography using a shutter speed lower than the flash synchronizing speed even in a wireless photography in a camera using a focal plane shutter.
It is another object of the invention to provide a flash system capable of selecting one of a plurality of flash light emission modes, including an automatic light control mode, a manual light emission mode, a multiple light emission mode, etc., and capable of concentrically managing the operation of a slave flash device by means of a master transmission device mounted on or incorporated in a camera.
It is a further object of the invention to provide a flash system capable of enabling confirmation as to whether a command from a master transmission device has been received by a slave flash device.
To attain the above objects, in accordance with one aspect of the invention, there is provided a flash system composed of a camera having a focal plane shutter and a slave flash device located at a distance from the camera, the camera comprising selection means for selecting a light emission mode from between a flash light emission mode and a flat light emission mode according to a controlled shutter speed, and transmission means for transmitting flash-device control information including the light emission mode to the slave flash device, the slave flash device comprising receiving means for receiving the flash-device control information, flash light emission means, and light emission control means for controlling the flash light emission means in the flash light emission mode or the flat light emission mode according to the received flash-device control information. The flash-device control information includes information for selecting one of the flash light emission mode and the flat light emission mode, and, if the flat light emission mode is selected, a shutter speed and a light emission time depending on a shutter blade speed.
In accordance with one aspect of the invention, there is provided a flash system composed of a camera and a slave flash device located at a distance from the camera, the camera comprising selection means for selecting a flash-device exposure mode according to a photo-taking condition, and transmission means for transmitting information on the selected flash-device exposure mode according to a photo-taking operation of the camera, the slave flash device comprising receiving means for receiving the information, flash light emission means, and light emission control means for controlling light emission of the flash light emission means according to the received information on the flash-device exposure mode.
In accordance with one aspect of the invention, there is provided a flash system composed of a camera and a slave flash device located at a distance from the camera, the camera comprising selection means for selecting a flash-device exposure mode according to a photo-taking condition, and transmission means for transmitting information on the selected flash-device exposure mode according to a photo-taking operation of the camera, the slave flash device comprising receiving means for receiving the information, flash light emission means, and display means for displaying information corresponding to the received information on the flash-device exposure mode.
In accordance with one aspect of the invention, there is provided a flash system in which optical communication from a master transmission device to a slave flash device is made so as to control the slave flash device, the master transmission device transmitting a plurality of groups of data, each group of data being composed of a digitally-coded light pulse string of a predetermined length, the plurality of groups of data being transmitted time-serially as a series of information.
In accordance with one aspect of the invention, there is provided a flash system in which transmission of information to a plurality of slave flash devices is performed by optical communication from a master flash device, a series of data composed of data for designating a particular slave flash device among the plurality of slave flash devices and data indicative of an amount of light emission of the designated slave flash device being transmitted by optical communication, and the designated slave flash device controlling an amount of light emission thereof according to the data indicative of the amount of light emission of the designated slave flash device.
In accordance with one aspect of the invention, there is provided a flash system in which optical communication is performed from a master flash device to a slave flash device having a plurality of receiving channels, the master flash device transmitting data indicative of a particular designated channel and data indicative of light emission information of the slave flash device, the slave flash device determining the data indicative of the designated channel received from the master flash device and, if coincidence of channels is determined, making light emission according to the light emission information.
In accordance with one aspect of the invention, there is provided a flash device releasably mountable on a camera, the flash device comprising mounting means for releasably mounting the flash device on the camera, flash light emission means, setting means for setting a slave mode, receiving means for receiving wireless control information, light emission control means for controlling the flash light emission means according to the received control information, detection means for detecting an operating state of the camera through a communication terminal with the camera, and setting canceling means for, when the operating state of the camera is detected by the detection means with the flash device set to the slave mode by the setting means and mounted on the camera, canceling the setting of the slave mode and enabling the flash light emission means to make light emission according to an instruction received from the camera through the communication terminal.
In accordance with one aspect of the invention, there is provided a flash system having a master transmission device including a camera, and one or a plurality of slave flash devices located at distances from the master transmission device, in which the slave flash device is controlled through communication from the master transmission device, the master transmission device comprising transmission means for transmitting control information including at least preliminary light emission information for giving an instruction for preliminary light emission to the slave flash device, the slave flash device comprising receiving means for receiving the control information from the master transmission device, light emission control means for controlling light emission of flash light emission means according to the received control information, preliminary light emission determining means for determining whether the flash light emission means can normally make preliminary light emission when the control information for the preliminary light emission has been received, and light emission inhibiting means for inhibiting main light emission when the preliminary light emission determining means determines that the flash light emission means can not normally make preliminary light emission.
In accordance with one aspect of the invention, there is provided a flash system having a master transmission device including a camera, and one or a plurality of slave flash devices located at distances from the master transmission device, in which the slave flash device is controlled through communication from the master transmission device, the master transmission device comprising transmission means for transmitting control information including at least preliminary light emission information for giving an instruction for preliminary light emission to the slave flash device, the slave flash device comprising receiving means for receiving the control information from the master transmission device, light emission control means for controlling light emission of flash light emission means according to the received control information, preliminary light emission determining means for determining whether the flash light emission means has normally made preliminary light emission when the control information for the preliminary light emission has been received, and light emission inhibiting means for inhibiting main light emission when the preliminary light emission determining means determines that the flash light emission means has not normally made preliminary light emission.
In accordance with one aspect of the invention, there is provided a flash system composed of a wireless flash-device control device and slave flash devices, the wireless flash-device control device being incorporated in or mounted on a camera and comprising test response command means, transmission means for transmitting flash-device control information to the slave flash devices, and setting means for setting number of groups to be controlled of the slave flash devices as being grouped, each of the slave flash devices comprising receiving means for receiving the flash-device control information, test response means, and test response control means for controlling the test response means according to the received flash-device control information, in which, in response to an operation of the test response command means, the wireless flash-device control device transmits to the slave flash devices through the transmission means flash-device control information related to a test response corresponding to the set number of groups, and the slave flash devices perform a test response according to the received flash-device control information related to the test response and the set number of groups.
In accordance with one aspect of the invention, there is provided a flash system composed of a wireless flash-device control device and a slave flash device, the wireless flash-device control device being incorporated in or mounted on a camera and comprising transmission means for transmitting flash-device control information to the slave flash device, the slave flash device comprising receiving means for receiving control information, flash light emission means, and light emission control means for controlling the flash light emission means according to the received control information, in which the wireless flash-device control device further comprises setting means for setting a frequency of multiple light emission and number-of-times-of-light-emission computing means for computing the number of times of light emission on the basis of a set shutter opening time and the frequency of multiple light emission, and transmits to the slave flash device through the transmission means flash-device control information including information related to the number of times of light emission computed by the number-of-times-of-light-emission computing means, and the slave flash device makes multiple light emission composed of a number of times of light emission designated on the basis of the information related to the number of times of light emission included in the received flash-device control information.
In accordance with one aspect of the invention, there is provided a flash system composed of a wireless flash-device control device and a slave flash device, the wireless flash-device control device being incorporated in or mounted on a camera and comprising transmission means for transmitting flash-device control information to the slave flash device, the slave flash device comprising receiving means for receiving control information, flash light emission means, and light emission control means for controlling the flash light emission means according to the received control information, in which the wireless flash-device control device further comprises setting means for setting a frequency of multiple light emission, transmits, prior to traveling of a shutter, to the slave flash device through the transmission means flash-device control information including information related to the frequency of multiple light emission, and transmits a light emission stop signal upon completion of a photo-taking operation, and the slave flash device makes multiple light emission with the light emission control means on the basis of the information related to the frequency of multiple light emission, and stops the multiple light emission upon receipt of the light emission stop signal.
In accordance with one aspect of the invention, there is provided a photo-taking apparatus arranged to control a predetermined operating state in response to a wireless signal from a master transmission device, the photo-taking apparatus comprising a computer arranged to control the operating state and having a first operation mode and a second operation mode in which the computer operates in a lower electric power consumption state than in the first operation mode, and a receiving circuit arranged to receive the wireless signal, in which the computer operates in the first operation mode during a first period of time, and, if the wireless signal is not received by the receiving circuit during the first period of time for the first operation mode, the computer shifts to the second operation mode.
In accordance with one aspect of the invention, there is provided a flash system composed of a camera having a focal plane shutter and a slave flash device located at a distance from the camera, the camera comprising selection means for selecting one of flash light emission and flat light emission, and transmission and light emission means for transmitting light-emission control information to the slave flash device and for making light emission according to the light-emission control information, the slave flash device comprising receiving means for receiving the light-emission control information, and flash light emission means, and being arranged to make preparation for light emission of the flash light emission means according to the received light-emission control information and to make light emission according to the light-emission control information in synchronism with light emission of the camera, in which, when the flat light emission is selected, the light emission of the transmission and light emission means is controlled by light emission control means for varying initial light emission intensity of the flat light emission.
The above and further objects and features of the invention will become apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the accompanying drawings.